Question

Define critical angle and refractive index

Answer 1

“Critical angle in optics refers to the angle of incidence, beyond which total internal reflection of light occurs. The path of a light ray incident upon a medium that has a lesser value of refractive index is bent away from the normal path. As a result, the exit angle of the ray is greater than the incident angle.”

Answer 2

The refractive index of second medium with respect to the first medium is defined as the ratio of the sine of the angle of incidence in the first medium to the sine of the angle of refraction in the second medium